There are a couple of technical tricks that can be used to find out the right solution.

You can use a spectrum analyzer software to find out which file has more harmonics than another, the most harmonics should indicate the wav file.

Due to some silence added in the beginning of the file during the conversion process the wav file is the only one that has a slightly different file size than the others. This way the wav can be identified for sure. Since it is possible to hear the 192kbps and 128kbps without a lot of trouble all files can be identified once the wav has been identified.

Listening to the MQ converted files of course made identifying the files easier.

The correct solution:

A: 320 KBPS
B: WAV
C: 192 KBPS
D: 128 KBPS

Results after filtering double votes from same IPs the results from the Poll:

The result show that the WAV, 320 and 192 were identified as the “WAV” equally and this indicates that (assuming that a part of it was coincidence) that at least about 65% of the listeners can not hear the difference between WAV and 320 Kbps and 192 Kbps.

The results clearly show that the 128Kbps mp3 can be identified with a high degree of certainty.

Interesting comments given on the subject:

If you decide to reconvert to another format it’s not optimal to have an mp3 file

Some people say that emotionally they could feel the difference

Some people say that when changing the speed of the song the differences become more obvious (I didn’t test)